1. Field of the Invention
The invention relates generally to the field of thermostats, and in particular to systems and methods for monitoring heating, ventilation, and air conditioning (HVAC) units using a thermostat.
2. Description of the Related Art
An energy management system (EMS) typically monitors and controls multiple endpoints such as HVAC units, lighting panels, natural gas consumption, refrigeration, temperature monitors, and other power consuming or monitoring devices located throughout one or more zones of a building or buildings. A monitoring device is mounted to the wall of such a building in or near an electrical room and is wired to common voltages at the electrical distribution panel (or breaker box) so as to receive voltage readings. The monitoring device is also wired to current transformers (CTs) coupled to the electrical lines at the electrical distribution panel so as to receive current readings from the electrical lines of one or more circuits, for example, an HVAC unit and/or lighting group. The monitor typically forwards this voltage/current data to a site controller, also mounted in the building, which in turn transmits power or consumption data to an off-site server for storage and processing. Each building also contains one or more thermostats mounted to the wall of the building, each associated with an HVAC unit. Each thermostat controls its corresponding HVAC unit based on the temperature setting and schedule. The monitors, thermostats, and site controller are wired together at each site to form the core of the local EMS hardware system. The monitored data is transmitted from the off-site server to a central control and monitoring EMS that is remote from the building or buildings being monitored. The monitored data is typically presented to a user/operator overseeing the operation of one or more of the buildings via a computer monitor coupled to the EMS.
As can be appreciated, while an EMS with such a configuration offers a highly flexible solution for large fleets of buildings under a common control, it also contains more components than necessary for some smaller facilities having few numbers of monitored endpoints. Further, the large number of components and remote communications of a typical cloud-based EMS can introduce latency into the system thereby preventing quick detection and response to HVAC problems reflected in the monitored data.